We’re currently working on defining a compact mode experience. I will post more details when we have more to share.
Density. However, two things:
1. How you define compact as being "more about a reduction in overall size which is most beneficial to smaller screens and mobile devices." I disagree with this. Compact is most beneficial to anyone who would like more screen real-estate. Not just smaller screens and mobile devices.
2. Give us the view option in the application. Why use a one size fits all model. That just seems lazy and dated.
Please stop the 'one size fits all' BS. Your audience isn't 12. This is (supposed to be) a professional tool. Just give us options to choose from like any good personalizable UI. Seems like you're wasting development energy and time trying to satisfy everyone with a single UI density.
If you're going to be replacing SFB, you absolutely need to have a contact list option/view. Really helps to see peoples current availability along with not having to remember everyone's name in a large org.